<form id="search" class="mt-4" action="//www.google.com/search" method="get" accept-charset="utf-8" target="_blank" _lpchecked="1">
  {{/** the keywords **/}}
  <input type="text" name="q" maxlength="20" placeholder="Search">
  <input type="hidden" name="sitesearch" value="{{ .Site.BaseURL }}">
  <button type="submit">搜索</button>
</form>